ABSTRACT
Until a few decades ago, purchase price was the only consideration when a decision was
made in regard to the purchase of a new item. The item could be as ordinary as an automobile or
as sophisticated as a warship or an air traffic control system. As systems became more complex
and as funds, public or private, became scarcer, costs, such as operational and maintenance costs,
became important considerations. The natural extension of these considerations was the notion of
system life. How long should we be concerned about the operation and maintenance costs?
